Patent Document 1 discloses a micro hardness meter that presses an indenter onto a test piece, detects the displacement of the indenter in response to its press load, and measures the hardness of the test piece. In this kind of micro hardness meter, the press load at which the indenter is pressed onto a test piece is very minute and the measurement result could be adversely affected, since the hardness meter itself might vibrate due to noise and vibration of surroundings.
On the other hand, Patent Document 2 discloses a testing machine that includes a preliminarily selected filter interposed in a circuit for extracting detection output of the test force applied to a test piece or elongation of the test piece in order to remove noises in the detection signal. In this testing machine, the noise removal of the detection output is done by using a filter characteristic selected from among a plurality of filter characteristics set beforehand.
[Patent Document 1] Japanese Laid-Open Application No. 05-85019.
[Patent Document 2] Japanese Patent Laid-Open Application No. 2005-331256